Keeping my parked domains safe?

Hi,

I own ~30 DR40+ domains all from Denmark. In Denmark, our Domainsystem allows anybody who finds out a domain is for sale, to request to overtake that domain, under the grounds that domain-trading inside the .dk-domain is not allowed.

Basically this means, if I place a "for sale" sign on my pages, they are free, up for grabs. Imagine that.

Okay, thats an obstacle, I have to work around: I have built 30 fairly similar but also visually different "coming soon" pages, and the domains are being sold off to the side elsewhere. My question is, I want to keep as much juice as possible, yet not expose the "coming soon" pages to archive.org or anything that can later devalue the future buyers credibility of the purchase.

What I am thinking of is this:

Content: Randomly generated design on a "Comming soon" page (already have this)
Header: Send out 503 "temp. down"
Robots: noindex, noarchive
Robots.txt: disallow all robots, including ahref, but excluding google (note, europe is like, 90% Google, if not more).

I am very unsure of the robots.txt part. All i want is to present content (to make my future ownership of the domains more plausible) and still not upset the flow of the juice

you should consider opening the smallest possible hosting package (coming soon page) and blaze the actual domain name within the text with all of the above as you mentioned that way your indicating that its not for sale as its "coming soon" and therefore its not up for grabs and the juice will be there if and when you decide to sell.

That's a really strange regulation, does it apply only to domains registered in Denmark or are there any other countries with the same exception? I own a few dk domains and I wasn't aware.